Resistor unit



Mach 1959 E. F. KELM 2, 7,330

RESISTOR UNIT Filed May 4, 1956 Enventor tvsesrr E KELM 1 Gttorneg nit Swwalh v RESISTOR UNIT Everett F. Kelm, Corning, N. Y., assignor to Corning 1 Glass Works, Corning, N. Y., a corporation of New York Application May 4, 1956, Serial No. 582,770 10 Claims. (Cl. 201-73) The present invention relates to resistor units, but is primarily concerned with the provision of an inexpensive cartridge type resistor unit ideally suited to use in a space heater, although in no respect limited to such use.

It has been common practice in the past to employ Edison base wire-wound heating units in reflector bowls of space heaters. Moreover, space heaters have been provided in which heat lamps of different forms have been similarly mounted in front of suitable reflectors.

According to the present invention a tubular or cartridge type of heating unit is provided having a conductive coating on its inner surface and having terminal posts at its opposite ends by means of which the tube may be supported and/or plugged into current supply clips mounted within a suitable frame, usually provided with a heat reflector. Obviously such frame may have provision for accommodating any number of resistor units in accordance with the heat output desired.

In the accompanying drawing, Fig. 1 shows in perspective, tubular resistor units embodying the invention mounted in clips of a simple form of heater frame.

Fig. 2 is a view on an enlarged scale of an end fragment of a resistor unit embodying the invention with part of the tubular support broken away.

Fig. 3 is a view taken on line 3-3 of Fig. 2.

Fig. 4 is a view taken on line 4-4 of Fig. 2.

Fig. 5 is a greatly enlarged sectional view of one end of the tubular portion of the resistor unit.

Figs. 6 and 7 are end and sectional views respectively depicting an alternative form of the invention.

Referring to the drawing in detail, the numeral 11 designates a tubular glass support whose wall is annularly constricted in each end region, as shown. The entire inner surface of tube 11 is provided with a conductive coating 12, such as tin oxide or the like, to a thickness imparting to it the desired resistance characteristic. The end regions of the tube wall including its constricted portions are overlaid with a metallic silver coating, such as 13 to serve as an end terminal for the coating 11.

Arranged within each end of the support 11 is a bar 15 of inorganic nonmetallic electrically conductive material, preferably composed of graphite, having its end surfaces such as 16 of a shape to form a surface that mates with the surface such as 17 of the constricted portion of the wall of support 11.

Also within the bore of support 11, there is arranged a circular disc 21 having a border portion 22 shaped to mate with the adjacent wall surface 23 of the support wall constriction. The bar 15 and disc 21 are tightly clamped in fixed relation to the support 11 by means of a headed pin 25 conveniently passing through apertures in bar 15 and disc 21 respectively. Pin seizing lips 26 formed from material of disc 21 are adapted to grip the pin 25 and hold the bar 15 and the disc tightly against the adjacent respective support wall surfaces 17 and 23. Graphite bar 15 is thus held in rigid intimate contact with the coating 13; and the pin 25, which extends beyond the support end, and the similar pin 27 at the other end of 2 the support 11 can be snapped into current supply clips 28 and 29carried by the frame 30.

Obviously if desired, the pins 25 and 27 may be threaded and conventional nuts employed to clamp the bars and discs such as 15 and 21 to support 11. The arrangement shown, however, speeds up assembly and is more economical in parts cost. Desirably the discs such as 21 have slots such as 31 extending inwardly from their peripheries at spaced intervals to impart greater resiliency thereto so as to reduce point loading on the support 11 over the surfaces such as 23. The disc 21 and the similar disc at the other end of support 11 are preferably provided with apertures such as 32 for permitting the free circulation of air through support 11 to maintain it at a lower operating temperature than were the heat confined within the tube as is the case of lamptype heater units.

In the alternative form of the invention, depicted in Figs. 6 and 7, the graphite bar 35, which is similar to bar 15, is provided with two passages through which the separate branches 36 and 37 of a bifurcated pin are passed. The disc 38 is substantially like disc 21 but has a larger passage therethrough. One end of a hollow post 40 occupies the passage in disc 38 to which it is riveted. The other end of post 40 has a reduced diameter opening flanked on two opposite sides with grooves into which the respective pin branches 36 and 37 are bent. Initially pin branches 36 and 37 for convenience of assembly are considerably longer than shown and, after being passed through post 40 and bent down into its grooves, are suitably clipped off close to the post, as shown. A post such as 40 is in certain instances preferable to the pin 25, while use of the bifurcated pin enables convenient and effective clamping of the bar 35 and disc 38 to the support in this alternative form of constriction.

What is claimed is:

1. In a resistor, a tubular support whose wall has an annular bore constriction adjacent an end thereof, a conductive coating on the inner surface of the support wall, a low resistance annular terminal for the conductive coating occupying the inner surface of the support wall in the region bridging its constriction, a bar of electrically conductive material within the support bore and arranged transversely thereof, such bar having end region surfaces mated against the inwardly facing surface of the support wall constriction, an end member occupying the support bore and having a border portion shaped to mate with the outwardly facing surface of the wall constriction, and means for clamping said bar and end member against such support surfaces.

2. A resistor such as defined by claim 1 wherein the means for clamping said bar and end member is integral with said end member.

3. A resistor such as defined by claim 1 wherein the clamping means is arranged along the axis of the support and has an end extending beyond the support end.

4. A resistor such as defined by claim 1 wherein the end member is in the form of a circular disc.

5. A resistor such as defined by claim 4 wherein the disc at spaced intervals about its periphery has slots extending inward toward its center.

6. A resistor such as defined by claim 1 wherein the conductive coating, the annular terminal strip, and the end member are all wholly within the confines of the support bore.

7. A resistor such as defined by claim 1 wherein said bar is composed of inorganic non-metallic electrically conductive material.

8. A resistor such as defined by claim 1 wherein said end member has a hollow tubular post associated therewith projected outwardly from the support end and wherein the clamping means comprises a bifurcated pin Patented Mar. 10, 1959- both branches of which pass through the bar and through such post and the free ends or which are turned down over the ends thereof to effect clamping of the bar and of the disc to such body.

- 9. A resistor such as defined by claim 8 wherein said tubular post is provided with channels occupied-by the turned down free ends of said pin.

10. A resistor such as defined by claim 8 wherein the tubular post is rigidly secured to the end member.

UNITED STATES PATENTS Scott et a1. Feb. 18, 1913 Van Nostrand May 23, 1933 Greenfield Nov. 13, 1934 Benkelman Oct. 17, 1939 Richardson Feb. 24, 1942 Oakley et a1. Oct. 4, 1949 Mochel Aug. 21, 1951 Crawford Feb. 1, 1955 Peck Sept. 13, 1955 

